Photoelectric conversion device, and photoelectric conversion system

Abstract

To improve a degree of freedom in arrangement of transistors.SOLUTION: Provided is a photoelectric conversion device that has an avalanche diode arranged on a first substrate having a first surface and a second surface opposed to the first surface. The avalanche diode has: a first semiconductor region of a first conductivity type arranged at a first depth; a second semiconductor region of a second conductivity type arranged at a second depth deeper than the first depth with respect to the second surface; a third semiconductor region arranged at a third depth deeper than the second depth with respect to the second surface; a fourth semiconductor region in contact with the third semiconductor region; first wiring connected with the first semiconductor region and provided at the second surface side to read out signals from the first semiconductor region; and second wiring provided on the first surface side. A difference between a potential applied to the first wiring and a potential applied to the second wiring is equal to or more than a breakdown voltage.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a photoelectric conversion device and a photoelectric conversion system using the same.

Background Art

[0002] Patent Document 1 describes a photoelectric conversion device provided with a through electrode for supplying a voltage to a semiconductor substrate on which a photoelectric conversion element is formed.

[0003] Patent Document 2 describes a photoelectric conversion device provided with an electrode for supplying a voltage to a semiconductor substrate on which an avalanche photodiode is formed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the structure described in Patent Document 1, there is a problem that the degree of freedom in transistor arrangement is limited in order to provide the through electrode. Further, in the structure described in Patent Document 2, there is a problem that the degree of freedom in the configuration of the portion where the anode voltage is supplied to the substrate and the portion where the cathode voltage is supplied to the substrate is limited in order to maintain the DCR (Dark Count Rate).

[0006] The present invention has been made in view of the above problems, and an object thereof is to improve the degree of freedom in the design of the photoelectric conversion element.

Means for Solving the Problems

[0007] One aspect of the present invention is a photoelectric conversion device having an avalanche diode disposed on a first substrate having a first surface and a second surface facing the first surface, wherein the avalanche diode has a first semiconductor region of a first conductivity type disposed to a first depth, a second semiconductor region of a second conductivity type disposed to a second depth deeper than the first depth relative to the second surface, a third semiconductor region disposed to a third depth deeper than the second depth relative to the second surface, a fourth semiconductor region in contact with the third semiconductor region, a first wiring connected to the first semiconductor region and provided on the second surface side for reading a signal from the first semiconductor region, and a second wiring provided on the first surface side, wherein the difference between the potential applied to the first wiring and the potential applied to the second wiring is greater than or equal to the breakdown voltage.

[0008] Another aspect of the present invention is a photoelectric conversion device comprising: a first substrate having a first surface to which light is incident and a second surface facing the first surface; and a second substrate laminated on the side of the first surface of the first substrate, wherein the first substrate includes a photoelectric conversion element comprising a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type; a third semiconductor region in contact with the second semiconductor region; a first wiring connected to the first semiconductor region for reading a signal from the first semiconductor region; and a second wiring provided on the side of the first surface for supplying potential to the first substrate, wherein the first substrate has a third surface facing the second surface, a fourth surface facing the third surface, and a transistor formed on the fourth surface which is part of a pixel circuit for processing a signal output from the photoelectric conversion element. [Effects of the Invention]

[0009] According to the present invention, the degree of freedom in transistor arrangement can be improved. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of a photoelectric conversion device according to an embodiment. [Figure 2] It is a schematic diagram of the PD substrate of the photoelectric conversion device according to the embodiment. [Figure 3] It is a schematic diagram of the circuit board of the photoelectric conversion device according to the embodiment. [Figure 4] It is a configuration example of the pixel circuit of the photoelectric conversion device according to the embodiment. [Figure 5] It is a schematic diagram showing the drive of the pixel circuit of the photoelectric conversion device according to the embodiment. [Figure 6] It is a configuration example of the pixel circuit of the photoelectric conversion element according to the embodiment. [Figure 7] It is a plan view of the chip end portion of the photoelectric conversion device according to the first embodiment. [Figure 8] It is a cross-sectional view of the photoelectric conversion device according to the first embodiment. [Figure 9] It is a plan view of the photoelectric conversion device according to the first embodiment. [Figure 10] It is a plan view of the photoelectric conversion device according to the first embodiment. [Figure 11] It is a cross-sectional view of the photoelectric conversion device according to the first embodiment. [Figure 12] It is a cross-sectional view of the photoelectric conversion device according to the first embodiment. [Figure 13] It is a cross-sectional view of the photoelectric conversion device according to the second embodiment. [Figure 14] It is a cross-sectional view of the photoelectric conversion device according to the second embodiment. [Figure 15] It is a cross-sectional view of the photoelectric conversion device according to the third embodiment. [Figure 16] It is a cross-sectional view of the photoelectric conversion device according to the third embodiment. [Figure 17] It is a cross-sectional view of the photoelectric conversion device according to the third embodiment. [Figure 18] It is a cross-sectional view of the photoelectric conversion device according to the fourth embodiment. [Figure 19] It is a plan view of the photoelectric conversion device according to the fourth embodiment. [Figure 20] It is a cross-sectional view of the photoelectric conversion device according to the fourth embodiment. [Figure 21]Cross-sectional view of a photoelectric conversion device according to the fourth embodiment. [Figure 22] Cross-sectional view of a photoelectric conversion device according to the fourth embodiment. [Figure 23] Cross-sectional view of a photoelectric conversion device according to the fifth embodiment. [Figure 24] Cross-sectional view of a photoelectric conversion device according to the sixth embodiment. [Figure 25] Functional block diagram of a photoelectric conversion system according to the seventh embodiment. [Figure 26] Functional block diagram of a photoelectric conversion system according to the eighth embodiment. [Figure 27] Functional block diagram of a photoelectric conversion system according to the ninth embodiment. [Figure 28] Functional block diagram of a photoelectric conversion system according to the tenth embodiment. [Figure 29] Functional block diagram of a photoelectric conversion system according to the eleventh embodiment.

Embodiments for Carrying Out the Invention

[0011] The following embodiments are for embodying the technical idea of the present invention and do not limit the present invention. The sizes and positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation. In the following description, the same components may be denoted by the same reference numerals and the description thereof may be omitted.

[0012] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In the following description, terms indicating specific directions and positions (for example, "up", "down", "right", "left", and other terms including those terms) are used as necessary. The use of those terms is for facilitating the understanding of the embodiments with reference to the drawings, and the technical scope of the present invention is not limited by the meanings of those terms.

[0013] In this specification, a plan view refers to viewing a semiconductor layer from a direction perpendicular to the light incident surface. A cross-sectional view refers to a surface perpendicular to the light incident surface of the semiconductor layer. If the light incident surface of the semiconductor layer is rough when viewed microscopically, the plan view is defined based on the light incident surface of the semiconductor layer as viewed macroscopically.

[0014] In the following description, the anode of the avalanche photodiode (APD) is set to a fixed potential, and the signal is taken from the cathode side. Therefore, the semiconductor region of the first conductivity type, which has majority carriers of the same polarity as the signal charge, is an N-type semiconductor region, and the semiconductor region of the second conductivity type, which has majority carriers of charges with a different polarity than the signal charge, is a P-type semiconductor region. Note that the present invention also applies when the cathode of the APD is set to a fixed potential and the signal is taken from the anode side. In this case, the semiconductor region of the first conductivity type, which has majority carriers of the same polarity as the signal charge, is a P-type semiconductor region, and the semiconductor region of the second conductivity type, which has majority carriers of charges with a different polarity than the signal charge, is an N-type semiconductor region. The following description will focus on the case where one node of the APD is set to a fixed potential, but the potentials of both nodes may fluctuate.

[0015] In this specification, when the term "impurity concentration" is used, it refers to the net impurity concentration after subtracting the amount compensated by reverse-conductivity impurities. In other words, "impurity concentration" refers to the NET doping concentration. The region where the doping concentration of P-type impurities is higher than that of N-type impurities is a P-type semiconductor region. Conversely, the region where the doping concentration of N-type impurities is higher than that of P-type impurities is an N-type semiconductor region.

[0016] The configuration common to each embodiment of the photoelectric conversion device and its driving method according to the present invention will be explained with reference to Figures 1 to 5.

[0017] Figure 1 shows the configuration of a stacked photoelectric converter 100 according to an embodiment of the present invention. The photoelectric converter 100 is constructed by stacking two substrates, a sensor substrate 11 and a circuit board 21, and electrically connecting them. The sensor substrate 11 has a first semiconductor layer having a photoelectric conversion element 102 (described later) and a first wiring structure. The circuit board 21 has a second semiconductor layer having a circuit such as a signal processing unit 103 (described later) and a second wiring structure. The photoelectric converter 100 is constructed by stacking the second semiconductor layer, the second wiring structure, the first wiring structure, and the first semiconductor layer in that order. The photoelectric converter described in each embodiment is a back-illuminated type photoelectric converter in which light is incident from the first surface and the circuit board is arranged on the second surface.

[0018] In the following description, the sensor substrate 11 and the circuit board 21 are explained using diced chips, but they are not limited to chips. For example, each substrate may be a wafer. Furthermore, each substrate may be stacked in wafer form and then diced, or it may be made into chips and then stacked and bonded together.

[0019] The sensor board 11 is provided with a pixel region 12, and the circuit board 21 is provided with a circuit region 22 for processing signals detected in the pixel region 12.

[0020] Figure 2 shows an example of the arrangement of the sensor substrate 11. Pixels 101, each having a photoelectric conversion element 102 including an avalanche photodiode (hereinafter referred to as APD), are arranged in a two-dimensional array in a planar view, forming a pixel region 12.

[0021] Pixel 101 is typically a pixel used to form an image, but when used in TOF (Time of Flight), it does not necessarily have to form an image. In other words, pixel 101 may be a pixel used to measure the time and amount of light that arrives.

[0022] Figure 3 is a diagram of the circuit board 21. It includes a signal processing unit 103 for processing the charge photoelectrically converted by the photoelectric conversion element 102 in Figure 2, a readout circuit 112, a control pulse generation unit 115, a horizontal scanning circuit unit 111, a signal line 113, and a vertical scanning circuit unit 110.

[0023] The photoelectric conversion element 102 in Figure 2 and the signal processing unit 103 in Figure 3 are electrically connected via connection wiring provided for each pixel.

[0024] The vertical scanning circuit section 110 receives control pulses supplied from the control pulse generation section 115 and supplies control pulses to each pixel. Logic circuits such as a shift register and an address decoder are used in the vertical scanning circuit section 110.

[0025] The signal output from the photoelectric conversion element 102 of the pixel is processed by the signal processing unit 103. The signal processing unit 103 is equipped with a counter and memory, and digital values ​​are stored in the memory.

[0026] The horizontal scanning circuit unit 111 inputs control pulses to the signal processing unit 103 to sequentially select each column in order to read the signal from the memory of each pixel in which the digital signal is held.

[0027] For the selected column, a signal is output from the signal processing unit 103 of the pixel selected by the vertical scanning circuit unit 110 to the signal line 113.

[0028] The signal output to signal line 113 is output via output circuit 114 to an external recording unit or signal processing unit of the photoelectric converter 100.

[0029] In Figure 2, the arrangement of photoelectric conversion elements in the pixel region may be one-dimensional. Furthermore, the effects of the present invention can be obtained even with just one pixel, and the case with one pixel is also included in the present invention. The function of the signal processing unit does not necessarily need to be provided for each photoelectric conversion element; for example, one signal processing unit may be shared by multiple photoelectric conversion elements, and signal processing may be performed sequentially.

[0030] As shown in Figures 2 and 3, multiple signal processing units 103 are arranged in the region that overlaps with the pixel region 12 in a plan view. The vertical scanning circuit unit 110, horizontal scanning circuit unit 111, column circuit 112, output circuit 114, and control pulse generation unit 115 are arranged so as to overlap between the edge of the sensor substrate 11 and the edge of the pixel region 12 in a plan view. In other words, the sensor substrate 11 has a pixel region 12 and a non-pixel region arranged around the pixel region 12, and the vertical scanning circuit unit 110, horizontal scanning circuit unit 111, column circuit 112, output circuit 114, and control pulse generation unit 115 are arranged in the region that overlaps with the non-pixel region in a plan view.

[0031] Figure 4 is an example of a block diagram including the equivalent circuits of Figures 2 and 3.

[0032] In Figure 2, the photoelectric conversion element 102 having the APD201 is provided on the sensor substrate 11, and the other components are provided on the circuit board 21.

[0033] The APD201 generates charge pairs corresponding to incident light through photoelectric conversion. A voltage VL (first voltage) is supplied to the anode of the APD201. In addition, a voltage VH (second voltage), which is higher than the voltage VL supplied to the anode, is supplied to the cathode of the APD201. A reverse bias voltage (a voltage above the breakdown voltage) is supplied to the anode and cathode so that the APD201 performs avalanche multiplication. By supplying such voltages, the charge generated by the incident light undergoes avalanche multiplication, and an avalanche current is generated.

[0034] Furthermore, when a reverse bias voltage is supplied, there are two modes: Geiger mode, in which the device operates with a potential difference between the anode and cathode greater than the breakdown voltage, and linear mode, in which the device operates with a potential difference between the anode and cathode near or below the breakdown voltage.

[0035] An APD operating in Geiger mode is called a SPAD. For example, voltage VL (first voltage) is -30V and voltage VH (second voltage) is 1V. The APD201 can be operated in linear mode or Geiger mode.

[0036] The quench element 202 is connected to the power supply that provides voltage VH and to the APD201. When the signal is amplified by avalanche multiplication, the quench element 202 functions as a load circuit (quench circuit), suppressing the voltage supplied to the APD201 and thereby suppressing avalanche multiplication (quench operation). In addition, the quench element 202 also works to restore the voltage supplied to the APD201 to voltage VH by flowing the current that compensates for the voltage drop caused by the quench operation (recharge operation).

[0037] The signal processing unit 103 includes a waveform shaping unit 210, a counter circuit 211, and a selection circuit 212. In this specification, the signal processing unit 103 only needs to include one of the waveform shaping unit 210, the counter circuit 211, or the selection circuit 212, and can also be called a pixel circuit that processes signals output from a photoelectric conversion element.

[0038] The waveform shaping unit 210 shapes the cathode potential change of the APD201 obtained during photon detection and outputs a pulse signal. For example, an inverter circuit can be used as the waveform shaping unit 210. Figure 4 shows an example in which one inverter is used as the waveform shaping unit 210, but a circuit in which multiple inverters are connected in series may be used, or other circuits that have a waveform shaping effect may be used.

[0039] The counter circuit 211 counts the pulse signal output from the waveform shaping unit 210 and holds the count value. When the control pulse pRES is supplied via the drive line 213, the signal held by the counter circuit 211 is reset.

[0040] The selection circuit 212 receives a control pulse pSEL from the vertical scanning circuit section 110 in Figure 3 via the drive line 214 (not shown in Figure 3) in Figure 4, which switches the electrical connection between the counter circuit 211 and the signal line 113. The selection circuit 212 includes, for example, a buffer circuit for outputting a signal.

[0041] A switch such as a transistor may be placed between the quench element 202 and the APD201, or between the photoelectric conversion element 102 and the signal processing unit 103, to switch the electrical connection. Similarly, the supply of voltage VH or voltage VL to the photoelectric conversion element 102 may be electrically switched using a switch such as a transistor.

[0042] In this embodiment, a configuration using a counter circuit 211 is shown. However, instead of the counter circuit 211, a photoelectric converter 100 may be used that acquires pulse detection timing using a Time to Digital Converter (TDC) and memory. In this case, the generation timing of the pulse signal output from the waveform shaping unit 210 is converted into a digital signal by the TDC. A control pulse pREF (reference signal) is supplied to the TDC via a drive line from the vertical scanning circuit unit 110 in Figure 1 to measure the timing of the pulse signal. The TDC acquires the signal as a digital signal when the input timing of the signal output from each pixel via the waveform shaping unit 210 is relative to the control pulse pREF.

[0043] Figure 5 schematically illustrates the relationship between the operation of the APD and the output signal.

[0044] Figure 5(a) is an excerpt of the APD201, quench element 202, and waveform shaping unit 210 from Figure 4. Here, the input side of the waveform shaping unit 210 is denoted as nodeA and the output side as nodeB. Figure 5(b) shows the waveform change at nodeA in Figure 5(a), and Figure 5(c) shows the waveform change at nodeB in Figure 5(a).

[0045] Between time t0 and time t1, a potential difference of VH-VL is applied to APD201 in Figure 5(a). When a photon is incident on APD201 at time t1, avalanche multiplication occurs in APD201, an avalanche multiplication current flows through the quench element 202, and the voltage at nodeA drops. As the voltage drop increases further and the potential difference applied to APD201 decreases, the avalanche multiplication of APD201 stops as at time t2, and the voltage level at nodeA stops dropping below a certain value. Subsequently, between time t2 and time t3, a current flows through nodeA to compensate for the voltage drop from voltage VL, and at time t3, nodeA settles to its original potential level. At this time, any portion of the output waveform at nodeA that exceeds a certain threshold is waveform-shaped by the waveform shaping unit 210 and output as a signal at nodeB.

[0046] Note that the arrangement of the signal lines 113, the column circuits 112, and the output circuits 114 is not limited to Figure 3. For example, the signal lines 113 may be arranged extending in the row direction, and the column circuits 112 may be located at the end of the signal lines 113.

[0047] Up to this point, the explanation has assumed the use of a pixel containing an APD as the photoelectric conversion element, but the photoelectric conversion element may also be a CMOS image sensor. Figure 6 shows an example of the equivalent circuit of a pixel in the photoelectric conversion device according to this embodiment.

[0048] In Figure 6, the photoelectric conversion element 102 having PD201 and the transfer transistor 202 are provided on the sensor substrate 11, while the other components are provided on the circuit board 21. Note that the arrangement shown in Figure 6 is just one example, and the components provided on the sensor substrate 11 and the components provided on the circuit board 21 can be selected as appropriate.

[0049] The signal processing unit 103 includes a transfer transistor TX, a floating diffusion transistor FD, a reset transistor RES, a source follower transistor SF, and a selection transistor SEL. Control signals for controlling each of these transistors are input to the gates of each transistor via control lines from the vertical scanning circuit 110 shown in Figure 1.

[0050] Furthermore, although the present invention has described a photoelectric conversion device in which multiple semiconductor substrates are stacked, a photoelectric conversion device in which pixels and circuits are formed on the same semiconductor substrate may also be used.

[0051] The following describes the photoelectric conversion device for each embodiment.

[0052] (First embodiment) A photoelectric conversion device according to the first embodiment will be described using Figures 7 to 12. As the first embodiment, a photoelectric conversion device in which pixels including a CMOS image sensor and circuits are formed on the same semiconductor substrate will be described.

[0053] Figure 7 shows a plan view of the chip edge. It shows one corner of a rectangular chip. The chip has a pixel region in which pixels are arranged in an array and a peripheral region surrounding it. The peripheral region is provided with pad electrodes for input and output of signals to the outside and pad openings formed in the substrate to expose the pad electrodes to the outside.

[0054] Figure 8 is a cross-sectional view of two pixels of the photoelectric conversion element 102 of the photoelectric conversion device according to the first embodiment, in a direction perpendicular to the plane direction of the substrate, and corresponds to the A-A'' cross-section in Figure 7.

[0055] The structure and function of the photoelectric conversion element 102 will now be described. The photoelectric conversion element 102 includes an N-type first semiconductor region 311 and a third semiconductor region 313. It also has a P-type fourth semiconductor region 314 and a fifth semiconductor region 315, which is also a P-type semiconductor region.

[0056] In this embodiment, in the cross-section shown in Figure 8, an N-type first semiconductor region 311 is formed near the second surface opposite the first surface which is the light incident surface, and an N-type third semiconductor region 313 is formed around it. A voltage is supplied to a P-type fifth semiconductor region 315 that overlaps the third semiconductor region 313 in a plan view from a contact electrode 324 provided in the wiring structure on the light incident surface side of the substrate.

[0057] Pixels are separated from each other by a trench-structured pixel isolation section 325, and a P-type fourth semiconductor region 314 formed around it separates adjacent photoelectric conversion elements by a potential barrier. Since photoelectric conversion elements are also separated by the potential of the fourth semiconductor region 314, a trench structure like the pixel isolation section 325 is not essential as a pixel isolation section, and even when a trench-structured pixel isolation section 325 is provided, its depth and position are not limited to the configuration shown in Figure 6. The pixel isolation section 325 may be a DTI (deep trench isolation) that penetrates the semiconductor layer, or it may be a DTI that does not penetrate the semiconductor layer. Metal may be embedded in the DTI to improve light shielding performance. The pixel isolation section 325 may consist of SiO, a fixed charge film, a metal member, Poly-Si, or a combination of several of these. The pixel isolation section 325 may be configured to surround the entire circumference of the photoelectric conversion element in a plan view, or it may be configured only on opposite sides of the photoelectric conversion element, for example.

[0058] On the light incident side of the semiconductor layer, a pinning film and a planarization film (not shown) are formed, and a microlens ML is further formed. A filter layer (not shown) may also be placed on the light incident side. Various optical filters such as color filters, infrared light cut filters, and monochrome filters can be used for the filter layer. For the color filter, RGB color filters, RGBW color filters, etc., can be used.

[0059] A wiring structure containing a conductor and an insulating film is provided on the surface of the semiconductor layer facing the light incident surface. An interlayer film, which is an insulating film, is provided between the wiring and the semiconductor layer, and between the wiring layers themselves.

[0060] Figure 9 is a pixel plan view of four pixels of a photoelectric converter according to the first embodiment. It shows a plan view from the light incident surface side. Figure 9(a) shows the arrangement of the contact electrode 324 and the pixel separation unit 325, and Figure 9(b) shows the wiring layout corresponding to Figure 9(a).

[0061] In the arrangement shown in Figure 9(a), each pixel is surrounded by a pixel separation section 325. Contact electrodes 324 are also placed at the four corners of each pixel. While it is possible to supply voltage to the fifth semiconductor region 315 if at least one contact electrode 324 is placed at each pixel, placing them at the four corners of the pixel helps maintain the symmetry of the voltage applied to each part of the pixel.

[0062] Furthermore, as shown in Figure 9(b), each of the wires connected to the contact electrode 324 that supplies voltage to each pixel is connected in a mesh-like manner and arranged to cover the pixel separation section 325.

[0063] It is desirable that the contact electrode 324 and the semiconductor substrate be joined with low resistance by ohmic contact. To this end, the contact electrode 324 may be formed by, for example, ion implantation of the contact region from the light incident surface side and activation of the region by laser annealing.

[0064] Figure 10 shows a modified version of the pixel plan view of four pixels in the photoelectric converter according to the first embodiment. Figure 10(a) shows the arrangement of the contact electrode 324 and the pixel separation section 325, and Figure 10(b) shows the wiring layout corresponding to Figure 10(a). In the plan view shown in Figure 9, the pixel separation section 325 surrounded each pixel, but it is also possible to have a structure in which the pixel separation section 325 is not formed at the corners of the pixels, and there is a gap between the pixel separation sections 325.

[0065] In this structure, compared to a structure where the pixel separation section 325 surrounds the entire circumference of the pixel, the wiring covering the 325 can be formed to be narrower, thus reducing the amount of incident light obstructed by the wiring. This is especially effective in reducing light loss due to wiring when the pixels are very small.

[0066] Furthermore, if a gap is provided in the pixel separation portion 325, it is possible to supply voltage to the pixels by supplying voltage to the fifth semiconductor region 315 in the outer peripheral region without forming contact electrodes 324 within the pixel region. However, a voltage drop may occur between the edge of the pixel region near the outer peripheral region and the central part of the pixel region far from the outer peripheral region, potentially resulting in a difference in the voltage applied to the pixels. Therefore, by providing contact electrodes 324 within the pixel region, it is possible to supply a constant voltage to the pixels throughout the entire pixel region. The number of contact electrodes 324 may be reduced, for example, by providing one contact electrode 324 for every multiple pixels (e.g., 4 pixels).

[0067] In the cross-sectional view shown in Figure 8, the pad electrodes were provided in the wiring structure on the light incident surface side of the substrate. However, the arrangement of the pad electrodes is not limited to this.

[0068] Figure 11 is a cross-sectional view of a photoelectric converter according to the first embodiment. In the photoelectric converter shown in Figure 11, the Pad electrode is located in a wiring structure on the side facing the light incident surface. The voltage input from the Pad electrode is connected to the wiring on the light incident surface side via a through-electrode provided in the outer peripheral region and penetrating the semiconductor substrate. The means for supplying the voltage may be, for example, a through-metal DTI (a device in which metal is embedded in a pixel separation portion 325 that penetrates the semiconductor layer) as shown in Figure 8, or a TSV (Through Silicon Via).

[0069] This configuration reduces the number of steps required to form pad openings on the substrate compared to the configuration shown in Figure 8. In the configuration shown in Figure 8, a pad opening process is required for the pad electrode provided in the wiring structure on the side facing the incident light surface, and another pad opening process is required for the pad electrode provided in the wiring structure on the side facing the incident light surface. On the other hand, to realize this configuration, only a pad opening process is required for the pad electrode provided in the wiring structure on the side facing the incident light surface.

[0070] Figure 12 shows a further modification of the structure shown in Figure 11. Figure 12 is a cross-sectional view of two pixels of the photoelectric converter according to the first embodiment.

[0071] In the configuration shown in Figure 12, as in Figure 11, pad electrodes are provided in the wiring structure on the side of the substrate facing the light incident surface. The difference from the configuration in Figure 11 is that voltage is supplied to the wiring on the light incident surface side via a P-type semiconductor region. In this configuration, it is not necessary to form through-electrodes that penetrate the semiconductor substrate as in the configuration shown in Figure 11.

[0072] (Second embodiment) A photoelectric conversion device according to the second embodiment will be described with reference to Figures 13 and 14. The second embodiment is a photoelectric conversion device in which pixels including a CMOS image sensor and circuits are formed on a plurality of semiconductor substrates. The following will mainly describe the differences from the first embodiment, and common explanations will be omitted.

[0073] Figure 13 shows a cross-sectional view of two pixels of a photoelectric converter according to the second embodiment. The first substrate, which has a first surface (light incident surface) and a second surface opposite to the first surface, is provided with a first semiconductor region 311, FD, and transfer gate, similar to the first embodiment. The second substrate, which is stacked on the first substrate, has a third surface opposite to the second surface and a fourth surface opposite to the third surface, and elements for reading pixel signals, such as a source follower transistor, reset transistor, and select transistor, are arranged on the fourth surface. The elements arranged on the second substrate are not limited to these and may also include subsequent signal processing circuits.

[0074] The first and second substrates are connected by contact electrodes (inter-substrate contacts), and signals for driving the gate of the transfer transistor and signals for outputting the voltage of the FD are transmitted across the substrates.

[0075] The photoelectric converter shown in Figure 13 has a first pad electrode and a second pad electrode. The first pad electrode is provided on the light incident surface side of the first substrate and is an electrode for supplying voltage to the wells of the first substrate via a contact electrode 324 provided on the light incident surface side of the first substrate. The second pad electrode is provided on the side of the second substrate facing the light incident surface and is an electrode for supplying voltage to the wells of the second substrate.

[0076] Here, different voltages may be supplied to the wells of the first substrate and the wells of the second substrate. By separating the supplied voltages, it is possible to isolate the effects of fluctuations in the power supply on each substrate, for example.

[0077] Figure 14 shows a modified example of the photoelectric conversion device according to the second embodiment.

[0078] In the configuration shown in Figure 14, the pad electrode is provided on the fourth side of the second substrate. This configuration uses the first pad electrode and the second pad electrode from Figure 13 as a common electrode.

[0079] The voltage supplied from the pad electrode on the second substrate is supplied to the well of the first substrate via a through-electrode or the like. Therefore, the signal for driving the gate of the transfer transistor, the signal for outputting the voltage of the FD, and the well potential are transmitted between the first and second substrates. Note that the through-electrode for transmitting the well potential between the first and second substrates only needs to be formed on the outer periphery of the pixel, for example, and it is not necessary for each pixel to have such wiring. One through-electrode may be provided for multiple pixels.

[0080] In this configuration, the number of steps required for the pad opening process can be reduced compared to the configuration shown in Figure 13, and the well potentials of the first and second substrates can be more easily standardized.

[0081] (Third embodiment) A photoelectric conversion device according to the third embodiment will be described using Figures 15 to 17. The third embodiment is a photoelectric conversion device in which pixels and circuits, including a CMOS image sensor, are formed on multiple semiconductor substrates and stacked in a different manner than the second embodiment. The following will mainly describe the differences from the second embodiment, and common explanations will be omitted.

[0082] Figure 15 shows a cross-sectional view of two pixels of a photoelectric converter according to the third embodiment. The first substrate on the light incident surface side is provided with a first semiconductor region 311, FD, and transfer gate, similar to the second embodiment. The second substrate, which is stacked on the first substrate, has elements for reading out pixel signals, such as a source follower transistor, a reset transistor, and a select transistor. The elements arranged on the second substrate are not limited to these and may also include subsequent signal processing circuits.

[0083] The first substrate and the second substrate are connected by the joining of metal wirings. At the joint surface between the first substrate and the second substrate, a first joint included in the first wiring structure of the first substrate and a second joint included in the second wiring structure of the second substrate are joined at the joint surface between the first and second wiring structures. In addition, a first insulating member included in the first wiring structure and a second insulating member included in the second wiring structure are joined at the joint surface between the first and second wiring structures. Metal wiring refers to wiring containing copper, for example.

[0084] In the photoelectric converter shown in Figure 15, similar to Figure 13, pad electrodes are provided on both the light incident surface side of the first substrate and the wiring layer on the side facing the light incident surface. Pad electrode 2 may be provided on the first wiring layer on the first substrate side of the bonding surface, or on the second wiring layer on the second substrate side of the bonding surface. By separating the pad electrodes for each well potential of each substrate, the effects of power supply fluctuations on each substrate can be isolated.

[0085] As shown in Figures 16 and 17, the pad electrode for supplying voltage to the well of the first substrate and the pad electrode for supplying voltage to the well of the second substrate may be a common electrode. In Figure 16, the pad electrode is provided on the wiring on the first substrate side of the bonding surface, and voltage is supplied to the well of the first substrate via a through electrode. In Figure 17, the pad electrode is provided on the wiring on the second substrate side of the bonding surface. Voltage is supplied to the well of the first substrate via a through electrode or metal bonding. In either case, it is possible to reduce the number of steps in the pad opening process.

[0086] (Fourth embodiment) A photoelectric conversion device according to the fourth embodiment will be described using Figures 18 to 28. The fourth embodiment is a photoelectric conversion device in which pixels including APDs and circuits are formed on the same semiconductor substrate. The following will mainly describe the differences from the first embodiment, and common explanations will be omitted.

[0087] Figure 18 is a cross-sectional view of two pixels of the photoelectric conversion element 102 of the photoelectric conversion device according to the fourth embodiment, in a direction perpendicular to the plane direction of the substrate, and corresponds to the A-A'' cross-section in Figure 7.

[0088] The structure and function of the photoelectric conversion element 102 will now be described. The photoelectric conversion element 102 includes an N-type first semiconductor region 311, a third semiconductor region 313, and a sixth semiconductor region 316. It also has a P-type second semiconductor region 312, a fourth semiconductor region 314, and a fifth semiconductor region 315.

[0089] In this embodiment, in the cross-section shown in Figure 18, an N-type first semiconductor region 311 is formed near the second surface (first depth) opposite the first surface of the semiconductor substrate, which is the light incident surface, and an N-type sixth semiconductor region 316 is formed around it. A P-type second semiconductor region 312 is formed at a position (second depth) that overlaps the first semiconductor region 311 and the sixth semiconductor region 316 in a plan view. A further N-type third semiconductor region 313 is positioned at a position (third depth) that overlaps the second semiconductor region 312 in a plan view, and an N-type semiconductor region is formed around it. Furthermore, a P-type fifth semiconductor region 315 is formed on the first surface side.

[0090] The first semiconductor region 311 has a higher N-type impurity concentration than the third semiconductor region 313. A PN junction is formed between the P-type second semiconductor region 312 and the N-type first semiconductor region 311. By making the impurity concentration of the second semiconductor region 312 lower than that of the first semiconductor region 311, all regions of the second semiconductor region 312 that overlap the center of the first semiconductor region in a plan view become a depletion layer region. At this time, the potential difference between the first semiconductor region 311 and the second semiconductor region 312 becomes larger than the potential difference between the second semiconductor region 312 and the third semiconductor region 313. Furthermore, this depletion layer region extends to a portion of the first semiconductor region 311, and a strong electric field is induced in the extended depletion layer region. Due to this strong electric field, avalanche multiplication occurs in the depletion layer region that extends to a portion of the first semiconductor region 311, and a current based on the amplified charge is output as a signal charge. When light incident on the photoelectric converter 102 is converted into electricity, and avalanche multiplication occurs in this depletion layer region (avalanche multiplication region), the generated charge of the first conductivity type is collected in the first semiconductor region 311.

[0091] In Figure 6, the sixth semiconductor region 316 and the third semiconductor region 313 are formed to be of roughly the same size, but the size of each semiconductor region is not limited to this. For example, the third semiconductor region 313 may be formed to be larger than the sixth semiconductor region 316, thereby collecting charge from a wider area to the first semiconductor region 311.

[0092] Furthermore, the sixth semiconductor region 316 may be a P-type semiconductor region instead of an N-type. In this case, the P-type impurity concentration in the sixth semiconductor region 316 is set lower than the P-type impurity concentration in the second semiconductor region 312. This is because if the impurity concentration in the sixth semiconductor region 316 is too high, an avalanche multiplication region will be formed between the sixth semiconductor region 316 and the first semiconductor region 311, causing the DCR (Dark Count Rate) to increase.

[0093] Pixels are separated from each other by a trench-structured pixel isolation section 325, and a P-type fourth semiconductor region 314 formed around it separates adjacent photoelectric conversion elements by a potential barrier. Since photoelectric conversion elements are also separated by the potential of the fourth semiconductor region 314, a trench structure like the pixel isolation section 325 is not essential as a pixel isolation section, and even when a trench-structured pixel isolation section 325 is provided, its depth and position are not limited to the configuration shown in Figure 6. The pixel isolation section 325 may be a DTI (deep trench isolation) that penetrates the semiconductor layer, or it may be a DTI that does not penetrate the semiconductor layer. Metal may be embedded in the DTI to improve light shielding performance. The pixel isolation section 325 may consist of SiO, a fixed charge film, a metal member, Poly-Si, or a combination of several of these. The pixel isolation section 325 may be configured to surround the entire circumference of the photoelectric conversion element in a plan view, or it may be configured only on opposite sides of the photoelectric conversion element, for example. A voltage may be applied to the embedded component to induce a charge at the trench interface, thereby suppressing the DCR.

[0094] A pinning film, a planarization film, and microlenses are further formed on the light incident surface side of the semiconductor layer. A filter layer (not shown) may also be placed on the light incident surface side. Various optical filters can be used for the filter layer, such as color filters, infrared cut filters, and monochrome filters. RGB color filters, RGBW color filters, etc., can be used for the color filter.

[0095] A wiring structure containing a conductor and an insulating film is provided on the surface of the semiconductor layer facing the light incident surface. An interlayer film, which is an insulating film, is provided between the wiring and the semiconductor layer, and between the wiring layers themselves.

[0096] In the photoelectric converter according to this embodiment, an anode wiring is provided on the light incident surface side of the semiconductor substrate, and a cathode wiring is provided on the surface opposite the light incident surface. The cathode wiring supplies a first voltage (cathode voltage) to the first semiconductor region 311, and the anode wiring supplies a second voltage (anode voltage) to the fourth semiconductor region 314 via the contact electrode 324.

[0097] When anode and cathode wiring are placed on the same wiring layer, there is a problem in that the wiring layout is restricted in order to maintain the voltage resistance between the wirings. In this configuration, anode and cathode wiring are placed on different wiring layers separated by a substrate, so there is a high degree of freedom in the wiring layout, which is advantageous, for example, when reducing the pixel size.

[0098] Figure 19 is a pixel plan view of four pixels of a photoelectric converter according to the fourth embodiment. It shows a plan view from a plane opposite to the light incident plane.

[0099] Figure 19(a) is a plan view showing the arrangement of the fourth semiconductor region 314 in a plan view from the first plane, and Figure 19(b) is a plan view from the second plane. Furthermore, Figure 19(c) shows a modified example of Figure 19(b).

[0100] As shown in Figures 19(a) and (b), a fourth semiconductor region 314 is continuously formed from the front to the back surface of the semiconductor substrate for pixel separation. Furthermore, in the conventional configuration where the anode potential is supplied from the second surface, it was necessary for the fourth semiconductor region to be formed on the surface facing the light incident surface, at least in the region where the contact potential is formed.

[0101] In the case of SPADs, a potential difference of nearly 30V is formed between the first semiconductor region 311, to which the cathode voltage is supplied to generate avalanche multiplication, and the fourth semiconductor region 314, to which the anode voltage is supplied. Therefore, it is desirable to keep the first semiconductor region 311 and the fourth semiconductor region 314 as far apart as possible. On the other hand, the smaller the distance between the first semiconductor region 311 and the fourth semiconductor region 314, the smaller the pixel size can be.

[0102] In the photoelectric converter according to this embodiment, where the anode wiring is arranged on the first surface and the anode potential is supplied from the light incident surface side, it is not necessary to form a fourth semiconductor region 314 on the second surface. This configuration enables further miniaturization of the pixels.

[0103] Figure 20 shows a cross-sectional view of the photoelectric converter shown in Figure 19(c).

[0104] To miniaturize the pixels, a fourth semiconductor region 314 is not provided near the second surface in the pixel region. However, a fourth semiconductor region 314 may be formed in the outer peripheral region.

[0105] Figure 21 shows an example of how to form the Pad electrodes of the photoelectric converter according to the fourth embodiment. Figure 21 shows an example in which Pad electrodes are formed on the wiring structure on the second surface side of the semiconductor substrate. The well potential is supplied to the contact electrode 324 on the first surface side via 325, etc.

[0106] Figure 22 shows that the wiring structure on the second surface includes cathode wiring and dummy wiring. Dummy wiring refers to floating wiring or wiring with a fixed potential. Possible fixed potentials include the anode potential, cathode potential, or an intermediate potential between the anode and cathode potentials. By providing such wiring, light transmitted to the second surface of the substrate is reflected into the pixel interior, improving photoelectric conversion efficiency and suppressing changes in breakdown voltage over time.

[0107] While extending the cathode wiring can achieve a similar effect for light reflection purposes, minimizing parasitic capacitance on the cathode electrode is advantageous for high-speed SPAD operation. Therefore, it is preferable to make the cathode electrode as small as possible. Consequently, using a separate wiring as a dummy wiring is useful.

[0108] (Fifth embodiment) A photoelectric conversion device according to the fifth embodiment will be described with reference to Figure 23. The fifth embodiment is a photoelectric conversion device in which pixels including APDs and circuits are formed on a plurality of semiconductor substrates. The following will mainly describe the differences from the fourth embodiment, and common explanations will be omitted.

[0109] Figure 23 shows a cross-sectional view of two pixels of the photoelectric converter according to the fifth embodiment. A PAD is provided on the first substrate on the light incident surface side, similar to the fourth embodiment. Elements such as a quench circuit, waveform shaping circuit, and signal processing circuit are arranged on the second substrate which is laminated on the first substrate. The elements arranged on the second substrate are not limited to these and may also include subsequent signal processing circuits.

[0110] The first substrate and the second substrate are connected by a contact electrode 324.

[0111] (Sixth Embodiment) A photoelectric conversion device according to the sixth embodiment will be described with reference to Figure 24. The sixth embodiment is a photoelectric conversion device in which pixels including APDs and circuits are formed on multiple semiconductor substrates and stacked in a different manner than the fifth embodiment. The following will mainly describe the differences from the fifth embodiment, and common explanations will be omitted.

[0112] Figure 24 shows a cross-sectional view of two pixels of the photoelectric converter according to the fifth embodiment. The first substrate on the light incident surface side is provided with an APD, similar to the fourth embodiment. Elements such as a quench circuit, waveform shaping circuit, and signal processing circuit are arranged on the second substrate which is laminated on the first substrate. The elements arranged on the second substrate are not limited to these and may also include subsequent signal processing circuits.

[0113] The first substrate and the second substrate are connected by the joining of metal wirings. At the joint surface between the first and second substrates, the metal wiring exposed on the surface of the first substrate is joined to the metal wiring exposed on the surface of the second substrate, and similarly, the insulating material on the surface of the first substrate is joined to the insulating material on the surface of the second substrate at the joint surface. The metal wiring is, for example, wiring containing copper.

[0114] (7th Embodiment) The photoelectric conversion system according to this embodiment will be described with reference to Figure 25. Figure 25 is a block diagram showing the schematic configuration of the photoelectric conversion system according to this embodiment.

[0115] The photoelectric conversion devices described in the first to sixth embodiments above are applicable to various photoelectric conversion systems. Examples of applicable photoelectric conversion systems include digital still cameras, digital camcorders, surveillance cameras, photocopiers, fax machines, mobile phones, in-vehicle cameras, and observation satellites. Camera modules, which include optical systems such as lenses and imaging devices, are also included in photoelectric conversion systems. Figure 25 shows a block diagram of a digital still camera as an example of these.

[0116] The photoelectric conversion system illustrated in Figure 25 includes an imaging device 1004, which is an example of a photoelectric conversion device, and a lens 1002 that forms an optical image of a subject onto the imaging device 1004. Furthermore, it has an aperture 1003 for varying the amount of light passing through the lens 1002, and a barrier 1001 for protecting the lens 1002. The lens 1002 and aperture 1003 are an optical system that focuses light onto the imaging device 1004. The imaging device 1004 is a photoelectric conversion device of any of the above embodiments, which converts the optical image formed by the lens 1002 into an electrical signal.

[0117] The photoelectric conversion system also includes a signal processing unit 1007, which is an image generation unit that generates an image by processing the output signal output from the imaging device 1004. The signal processing unit 1007 performs various corrections and compressions as needed and outputs the image data. The signal processing unit 1007 may be formed on the semiconductor substrate on which the imaging device 1004 is mounted, or it may be formed on a semiconductor substrate separate from the imaging device 1004.

[0118] The photoelectric conversion system further includes a memory unit 1010 for temporarily storing image data, and an external interface unit (external I / F unit) 1013 for communicating with an external computer or the like. Furthermore, the photoelectric conversion system includes a recording medium 1012 such as a semiconductor memory for recording or reading imaging data, and a recording medium control interface unit (recording medium control I / F unit) 1011 for recording or reading data from the recording medium 1012. The recording medium 1012 may be built into the photoelectric conversion system or may be detachable.

[0119] Furthermore, the photoelectric conversion system includes an overall control / calculation unit 1009 that controls various calculations and the entire digital still camera, and a timing generation unit 1008 that outputs various timing signals to the imaging device 1004 and the signal processing unit 1007. Here, the timing signals and the like may be input from an external source, and the photoelectric conversion system only needs to have at least the imaging device 1004 and the signal processing unit 1007 that processes the output signals output from the imaging device 1004.

[0120] The imaging device 1004 outputs the imaging signal to the signal processing unit 1007. The signal processing unit 1007 performs predetermined signal processing on the imaging signal output from the imaging device 1004 and outputs image data. The signal processing unit 1007 generates an image using the imaging signal.

[0121] Thus, according to this embodiment, a photoelectric conversion system can be realized by applying a photoelectric conversion device (imaging device) of any of the above embodiments.

[0122] (Eighth embodiment) The photoelectric conversion system and mobile unit of this embodiment will be described with reference to Figure 26. Figure 26 is a diagram showing the configuration of the photoelectric conversion system and mobile unit of this embodiment.

[0123] Figure 26(a) shows an example of a photoelectric conversion system related to an in-vehicle camera. The photoelectric conversion system 2300 has an imaging device 2310. The imaging device 2310 is a photoelectric conversion device as described in any of the embodiments above. The photoelectric conversion system 2300 has an image processing unit 2312 that performs image processing on a plurality of image data acquired by the imaging device 2310, and a parallax acquisition unit 2314 that calculates parallax (phase difference of parallax images) from a plurality of image data acquired by the photoelectric conversion system 2300. The photoelectric conversion system 2300 also has a distance acquisition unit 2316 that calculates the distance to an object based on the calculated parallax, and a collision determination unit 2318 that determines whether or not there is a possibility of collision based on the calculated distance. Here, the parallax acquisition unit 2314 and the distance acquisition unit 2316 are examples of distance information acquisition means that acquire distance information to an object. That is, distance information is information related to parallax, defocus amount, distance to an object, etc. The collision determination unit 2318 may use any of this distance information to determine the possibility of a collision. The means for acquiring distance information may be implemented by specially designed hardware or by a software module. It may also be implemented by an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a combination thereof.

[0124] The photoelectric conversion system 2300 is connected to the vehicle information acquisition device 2320 and can acquire vehicle information such as vehicle speed, yaw rate, and steering angle. The photoelectric conversion system 2300 is also connected to the control ECU 2330, which is a control unit that outputs a control signal to generate braking force on the vehicle based on the judgment result of the collision judgment unit 2318. The photoelectric conversion system 2300 is also connected to the warning device 2340, which issues a warning to the driver based on the judgment result of the collision judgment unit 2318. For example, if the collision judgment result of the collision judgment unit 2318 indicates a high probability of collision, the control ECU 2330 performs vehicle control to avoid a collision or mitigate damage by applying the brakes, releasing the accelerator, or suppressing engine output. The warning device 2340 warns the user by sounding an alarm, displaying warning information on a screen such as a car navigation system, or vibrating the seat belt or steering wheel.

[0125] In this embodiment, the photoelectric conversion system 2300 images the area around the vehicle, for example, the front or rear. Figure 26(b) shows the photoelectric conversion system when imaging the area in front of the vehicle (imaging range 2350). The vehicle information acquisition device 2320 sends instructions to the photoelectric conversion system 2300 or the imaging device 2310. This configuration can further improve the accuracy of distance measurement.

[0126] The above example illustrates control to prevent collisions with other vehicles, but it can also be applied to control systems that automatically follow other vehicles or automatically drive to prevent vehicles from straying from their lanes. Furthermore, the photoelectric conversion system can be applied not only to vehicles such as the vehicle itself, but also to mobile objects (mobile devices) such as ships, aircraft, or industrial robots. In addition, it can be applied not only to mobile objects but also to a wide range of devices that utilize object recognition, such as intelligent transportation systems (ITS).

[0127] (Ninth embodiment) The photoelectric conversion system of this embodiment will be described with reference to Figure 27. Figure 27 is a block diagram showing an example configuration of a distance image sensor, which is the photoelectric conversion system of this embodiment.

[0128] As shown in Figure 27, the distance image sensor 401 is configured to include an optical system 407, a photoelectric converter 408, an image processing circuit 404, a monitor 405, and a memory 406. The distance image sensor 401 receives light (modulated light or pulsed light) that is projected from the light source device 411 toward the subject and reflected from the surface of the subject, thereby acquiring a distance image corresponding to the distance to the subject.

[0129] The optical system 407 is composed of one or more lenses and guides the image light (incident light) from the subject to the photoelectric converter 408, where it forms an image on the light-receiving surface (sensor part) of the photoelectric converter 408.

[0130] The photoelectric converter 408 is one of the photoelectric converters from each of the embodiments described above, and a distance signal indicating the distance obtained from the light received signal output from the photoelectric converter 408 is supplied to the image processing circuit 404.

[0131] The image processing circuit 404 performs image processing to construct a distance image based on the distance signal supplied from the photoelectric converter 408. The distance image (image data) obtained through this image processing is then supplied to the monitor 405 for display or supplied to the memory 406 for storage (recording).

[0132] With the distance image sensor 401 configured in this way, by applying the photoelectric conversion device described above, the characteristics of the pixels are improved, and for example, more accurate distance images can be acquired.

[0133] (Tenth embodiment) The photoelectric conversion system of this embodiment will be described with reference to Figure 28. Figure 28 is a diagram showing an example of a schematic configuration of an endoscopic surgical system, which is the photoelectric conversion system of this embodiment.

[0134] Figure 28 illustrates a surgeon (physician) 1131 performing surgery on a patient 1132 on a patient bed 1133 using an endoscopic surgical system 1150. As shown in the figure, the endoscopic surgical system 1150 consists of an endoscope 1100, surgical instruments 1110, and a cart 1134 equipped with various devices for endoscopic surgery.

[0135] The endoscope 1100 consists of a barrel 1101, the tip of which is inserted into the body cavity of the patient 1132 for a predetermined length, and a camera head 1102 connected to the base end of the barrel 1101. In the illustrated example, the endoscope 1100 is shown as a so-called rigid endoscope having a rigid barrel 1101, but the endoscope 1100 may also be configured as a so-called flexible endoscope having a flexible barrel.

[0136] An opening into which an objective lens is fitted is provided at the tip of the endoscope tube 1101. A light source device 1203 is connected to the endoscope 1100, and the light generated by the light source device 1203 is guided to the tip of the endoscope tube by a light guide extending inside the endoscope tube 1101, and is irradiated through the objective lens towards the object to be observed inside the body cavity of the patient 1132. The endoscope 1100 may be a straight-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0137] The camera head 1102 contains an optical system and a photoelectric converter. Reflected light from the object being observed (observation light) is focused by the optical system into the photoelectric converter. The photoelectric converter converts the observation light into electrical signals, generating an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The photoelectric converter can be any of the photoelectric converters described in the embodiments described above. The image signal is transmitted as RAW data to the camera control unit (CCU) 1135.

[0138] The CCU1135 consists of a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and other components, and comprehensively controls the operation of the endoscope 1100 and the display device 1136. Furthermore, the CCU1135 receives an image signal from the camera head 1102 and performs various image processing operations on that image signal, such as development processing (demosaic processing), to display the image based on that image signal.

[0139] The display device 1136 displays an image based on an image signal that has been processed by the CCU 1135, under control from the CCU 1135.

[0140] The light source device 1203 consists of a light source such as an LED (Light Emitting Diode) and supplies illumination light to the endoscope 1100 when photographing the surgical area, etc.

[0141] The input device 1137 is an input interface for the endoscopic surgical system 1150. The user can input various types of information and instructions to the endoscopic surgical system 1150 via the input device 1137.

[0142] The treatment instrument control device 1138 controls the driving of the energy treatment instrument 1112 for purposes such as tissue cauterization, incision, or blood vessel sealing.

[0143] The light source device 1203, which supplies illumination light to the endoscope 1100 when photographing the surgical area, can be composed of, for example, an LED, a laser light source, or a combination thereof. When the white light source is composed of a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, so the white balance of the captured image can be adjusted in the light source device 1203. In this case, it is also possible to capture images corresponding to each of the RGB colors in time-division by irradiating the observation target with laser light from each of the RGB laser light sources in time-division and controlling the drive of the image sensor of the camera head 1102 in synchronization with the irradiation timing. According to this method, a color image can be obtained without providing a color filter on the image sensor.

[0144] Furthermore, the light source device 1203 may be controlled to change the intensity of the light it outputs at predetermined time intervals. By controlling the drive of the image sensor of the camera head 1102 in synchronization with the timing of the change in light intensity, images can be acquired in time-division order, and these images can be combined to generate high dynamic range images without so-called black crushing and white clipping.

[0145] Furthermore, the light source device 1203 may be configured to supply light in a predetermined wavelength band corresponding to special light observation. In special light observation, for example, the wavelength dependence of light absorption in body tissue is utilized. Specifically, by irradiating with narrowband light compared to the irradiation light used during normal observation (i.e., white light), predetermined tissues such as blood vessels on the surface of mucosa can be imaged with high contrast. Alternatively, in special light observation, fluorescence observation may be performed to obtain an image from fluorescence generated by irradiation with excitation light. In fluorescence observation, excitation light can be irradiated onto body tissue and fluorescence from the body tissue can be observed, or a reagent such as indocyanine green (ICG) can be injected into body tissue and excitation light corresponding to the fluorescence wavelength of the reagent can be irradiated onto the body tissue to obtain a fluorescence image. The light source device 1203 may be configured to supply narrowband light and / or excitation light corresponding to such special light observation.

[0146] (11th embodiment) The photoelectric conversion system of this embodiment will be described using Figures 29(a) and (b). Figure 29(a) illustrates the eyeglasses 1600 (smart glasses), which are the photoelectric conversion system of this embodiment. The eyeglasses 1600 have a photoelectric conversion device 1602. The photoelectric conversion device 1602 is the photoelectric conversion device described in each of the embodiments described above. In addition, a display device including a light-emitting device such as an OLED or LED may be provided on the back side of the lens 1601. There may be one or more photoelectric conversion devices 1602. In addition, multiple types of photoelectric conversion devices may be used in combination. The arrangement position of the photoelectric conversion device 1602 is not limited to that shown in Figure 29(a).

[0147] The eyeglasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the photoelectric converter 1602 and the display device. The control device 1603 also controls the operation of the photoelectric converter 1602 and the display device. The lens 1601 has an optical system formed therein for focusing light onto the photoelectric converter 1602.

[0148] Figure 29(b) illustrates a pair of glasses 1610 (smart glasses) relating to one application example. The glasses 1610 have a control device 1612, which is equipped with a photoelectric converter equivalent to a photoelectric converter 1602 and a display device. The lens 1611 has an optical system formed therein for projecting light emitted from the photoelectric converter in the control device 1612 and from the display device, and an image is projected onto the lens 1611. The control device 1612 functions as a power supply that provides power to the photoelectric converter and the display device, and also controls the operation of the photoelectric converter and the display device. The control device may have a gaze detection unit that detects the wearer's gaze. Gaze detection may use infrared light. The infrared light emitter emits infrared light towards the eyeball of the user who is fixating on the displayed image. An image capture image of the eyeball is obtained by detecting the reflected light from the eyeball of the emitted infrared light with an imaging unit having a light-receiving element. By having a reduction means that reduces the light from the infrared light emitter to the display unit in planar view, the deterioration of image quality is reduced.

[0149] The user's gaze towards the displayed image is detected from an image of the eyeball obtained by imaging with infrared light. Any known method can be applied to gaze detection using an image of the eyeball. For example, a gaze detection method based on the Purkinje image obtained by the reflection of the irradiated light from the cornea can be used.

[0150] More specifically, gaze detection processing is performed based on the pupil-corneal reflection method. Using the pupil-corneal reflection method, a gaze vector representing the orientation (rotation angle) of the eyeball is calculated based on the pupil image and Purkinje image contained in the captured image of the eyeball, thereby detecting the user's gaze.

[0151] The display device of this embodiment includes a photoelectric converter having a light-receiving element, and may control the display image of the display device based on the user's gaze information from the photoelectric converter.

[0152] Specifically, the display device determines a first field of view that the user is fixated on, and a second field of view other than the first field of view, based on gaze information. The first and second field of view may be determined by the control device of the display device, or they may be determined by an external control device and received. Within the display area of ​​the display device, the display resolution of the first field of view may be controlled to be higher than that of the second field of view. In other words, the resolution of the second field of view may be lower than that of the first field of view.

[0153] Furthermore, the display area may have a first display area and a second display area different from the first display area, and a higher priority area may be determined from the first and second display areas based on line-of-sight information. The first and second field-of-sight areas may be determined by the control device of the display device, or they may be determined by an external control device and received. The resolution of the higher priority area may be controlled to be higher than the resolution of the areas other than the higher priority area. In other words, the resolution of areas with relatively lower priority may be set lower.

[0154] AI may be used to determine the first field of view area and the areas with higher priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to the target object at the end of the line of sight from the image of the eye, using the image of the eye and the direction the eye was actually looking in that image as training data. The AI ​​program may be installed in the display device, the photoelectric converter, or an external device. If installed in an external device, it will be transmitted to the display device via communication.

[0155] When display control is based on visual detection, this method is preferably applicable to smart glasses that further include a photoelectric converter for capturing images of the surrounding environment. The smart glasses can display the captured external information in real time.

[0156] [Modified Embodiment] The present invention is not limited to the embodiments described above and can be modified in various ways.

[0157] For example, examples in which some configurations of one embodiment are added to other embodiments, or in which some configurations of other embodiments are replaced, are also included as embodiments of the present invention.

[0158] Furthermore, the photoelectric conversion systems shown in the seventh and eighth embodiments above are merely examples of photoelectric conversion systems to which the photoelectric conversion device can be applied, and the photoelectric conversion systems to which the photoelectric conversion device of the present invention can be applied are not limited to the configurations shown in Figures 25 to 26. The same applies to the ToF system shown in the ninth embodiment, the endoscope shown in the tenth embodiment, and the smart glasses shown in the eleventh embodiment.

[0159] It should be noted that the above embodiments are merely examples of how the present invention can be implemented, and the technical scope of the present invention should not be interpreted as being limited by them. In other words, the present invention can be implemented in various forms without departing from its technical concept or its main features.

[0160] Furthermore, this disclosure includes the following components.

[0161] (Configuration 1) A photoelectric conversion device having an avalanche photodiode disposed on a first substrate having a first surface and a second surface facing the first surface. The avalanche photodiode has a first semiconductor region of a first conductivity type disposed at a first depth, and a second semiconductor region of a second conductivity type disposed at a second depth which is deeper than the first depth relative to the second surface. Furthermore, it has a third semiconductor region disposed at a third depth which is deeper than the second depth relative to the second surface, and a fourth semiconductor region in contact with the third semiconductor region. It has a first wiring connected to the first semiconductor region and provided on the second surface side for reading signals from the first semiconductor region, and a second wiring provided on the first surface side. The difference between the potential applied to the first wiring and the potential applied to the second wiring is greater than or equal to the breakdown voltage.

[0162] (Configuration 2) The photoelectric conversion device according to Configuration 1, characterized in that the fourth semiconductor region is not arranged on the second surface.

[0163] (Configuration 3) The photoelectric conversion device according to Configuration 1 or 2, wherein the device has a third wiring formed in a wiring structure laminated on the second surface side of the first substrate, and the third wiring is not electrically connected to the first substrate.

[0164] (Configuration 4) A photoelectric conversion device according to any one of Configurations 1 to 3, wherein the second wiring is supplied with an external potential via the fourth wiring, and the second wiring is supplied with an external potential via the fourth wiring.

[0165] (Configuration 5) The photoelectric conversion device according to any one of 1 to 4, wherein the second wiring is supplied with potential from the outside via the fifth wiring, and the second wiring has a fifth wiring formed in a wiring structure laminated on the second surface side of the first substrate.

[0166] (Configuration 6) The photoelectric conversion device according to any one of 1 to 5, characterized in that the avalanche photodiode has a fifth semiconductor region provided in contact with the edge of the fourth semiconductor region.

[0167] (Configuration 7) The photoelectric conversion device according to Configuration 6, characterized in that the second wiring supplies potential to the third semiconductor region via the fifth semiconductor region.

[0168] (Configuration 8) The photoelectric conversion device according to Configuration 5, characterized in that the second wiring and the fifth wiring are connected by an electrode that penetrates the first substrate.

[0169] (Configuration 9) A photoelectric conversion device according to any one of Configurations 1 to 8, wherein the first substrate has a second substrate laminated on the second surface side, and the second substrate has a third surface facing the second surface and a fourth surface facing the third surface. The fourth surface has a transistor which is part of a pixel circuit that processes the signal output from the avalanche photodiode, and the third surface has a fifth semiconductor region to which a voltage is supplied.

[0170] (Configuration 10) A photoelectric conversion device according to any one of Configurations 1 to 9, comprising: a first substrate; a second substrate; a first wiring structure laminated on the second surface side of the first substrate; and a second wiring structure disposed between the first wiring structure and the second substrate. A first joint included in the first wiring structure and a second joint included in the second wiring structure are joined at the joint surface between the first wiring structure and the second wiring structure. A first insulating member included in the first wiring structure and a second insulating member included in the second wiring structure are joined at the joint surface between the first wiring structure and the second wiring structure.

[0171] (Configuration 11) A photoelectric conversion device comprising a first substrate having a first surface to which light is incident and a second surface facing the first surface, and a second substrate laminated on the side of the first surface of the first substrate. The first substrate has a photoelectric conversion element including a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type, and a third semiconductor region in contact with the second semiconductor region. Furthermore, it includes a first wiring connected to the first semiconductor region and reading a signal from the first semiconductor region, and a second wiring provided on the side of the first surface and supplying potential to the first substrate. The first substrate is characterized by having a third surface facing the second surface, a fourth surface facing the third surface, and a transistor formed on the fourth surface which is part of a pixel circuit that processes a signal output from the photoelectric conversion element.

[0172] (Configuration 12) The photoelectric conversion device according to Configuration 11, wherein the second wiring is supplied with potential from the outside via the fifth wiring, and a fifth wiring is formed in a wiring structure laminated on the first surface side of the first substrate.

[0173] (Configuration 13) The photoelectric conversion device according to 12, characterized in that the second wiring and the fifth wiring are connected by electrodes that penetrate the first substrate.

[0174] (Configuration 14) A photoelectric conversion device according to any one of Configurations 11 to 13, comprising: a first substrate; a second substrate; a first wiring structure laminated on the first surface side of the second substrate; and a second wiring structure disposed between the first wiring structure and the second substrate. A first joint included in the first wiring structure and a second joint included in the second wiring structure are joined at the joint surface between the first wiring structure and the second wiring structure. A first insulating member included in the first wiring structure and a second insulating member included in the second wiring structure are joined at the joint surface between the first wiring structure and the second wiring structure.

[0175] (Configuration 15) A photoelectric conversion system characterized by comprising a photoelectric conversion device described in any of Configurations 1 to 14, and a signal processing unit that generates an image using the signal output by the photoelectric conversion device.

[0176] (Configuration 16) A mobile body comprising a photoelectric converter according to any one of Configurations 1 to 15, characterized in that it has a control unit that controls the movement of the mobile body using a signal output by the photoelectric converter. [Explanation of symbols]

[0177] 100 Photoelectric converter 102 Avalanche Photodiode 311 First Semiconductor Area 312 The second semiconductor area 313 The Third Semiconductor Domain

Claims

1. A photoelectric conversion device having an avalanche photodiode disposed on a first substrate having a first surface and a second surface facing the first surface, wherein the avalanche photodiode includes: a first semiconductor region of a first conductivity type disposed at a first depth; a second semiconductor region of a second conductivity type disposed at a second depth deeper than the first depth with respect to the second surface; a third semiconductor region disposed at a third depth deeper than the second depth with respect to the second surface; a fourth semiconductor region in contact with the third semiconductor region; a first wiring electrically connected to the first semiconductor region and provided on the second surface side; a second wiring electrically connected to the fourth semiconductor region and provided on the first surface side; and a fourth wiring formed in a wiring structure laminated on the second surface side of the first substrate, wherein a difference between a voltage applied to the first wiring and a voltage applied to the second wiring is configured to be equal to or greater than a breakdown voltage, and the second wiring is supplied with a potential from the outside via the fourth wiring. The photoelectric conversion device is characterized by this.

2. The photoelectric conversion device according to claim 1, wherein the fourth semiconductor region is not disposed on the second surface.

3. The photoelectric conversion device according to claim 1, further comprising a third wiring formed in a wiring structure laminated on the second surface side of the first substrate, wherein the third wiring is not electrically connected to the first substrate.

4. The photoelectric conversion device according to claim 1, wherein the avalanche photodiode has a fifth semiconductor region provided in contact with an end portion of the fourth semiconductor region.

5. The photoelectric conversion device according to claim 4, wherein the second wiring supplies a potential to the third semiconductor region via the fifth semiconductor region.

6. The photoelectric conversion device according to claim 1, further comprising a second substrate laminated on the second surface side of the first substrate, wherein the second substrate has a third surface facing the second surface and a fourth surface facing the third surface, and has a transistor which is a part of a pixel circuit for processing a signal output from the avalanche photodiode on the fourth surface, and a fifth semiconductor region to which a voltage is supplied is provided on the third surface.

7. The first substrate, a second substrate, a first wiring structure laminated on the second surface side of the first substrate, and a second wiring structure disposed between the first wiring structure and the second substrate. The first photoelectric conversion device according to claim 1, characterized in that a first joint portion included in the first wiring structure and a second joint portion included in the second wiring structure are joined at a joint surface between the first wiring structure and the second wiring structure, and a first insulating member included in the first wiring structure and a second insulating member included in the second wiring structure are joined at the joint surface between the first wiring structure and the second wiring structure.

8. A photoelectric conversion device having an avalanche photodiode disposed on a first substrate having a first surface and a second surface facing the first surface, The avalanche photodiode includes: A first semiconductor region of a first conductivity type disposed at a first depth; A second semiconductor region of a second conductivity type disposed at a second depth deeper than the first depth with respect to the second surface; A third semiconductor region disposed at a third depth deeper than the second depth with respect to the second surface; A fourth semiconductor region in contact with the third semiconductor region; A first wiring electrically connected to the first semiconductor region and provided on the second surface side; A second wiring electrically connected to the fourth semiconductor region and provided on the first surface side; And a fifth wiring formed in a wiring structure laminated on the first surface side of the first substrate. The difference between the voltage applied to the first wiring and the voltage applied to the second wiring is configured to be equal to or greater than the breakdown voltage. The second wiring is characterized in that it is supplied with a potential from the outside via the fifth wiring.

9. The photoelectric conversion device according to claim 8, characterized in that the fourth semiconductor region is not disposed on the second surface.

10. It has a third wiring formed in a wiring structure laminated on the second surface side of the first substrate, The photoelectric conversion device according to claim 8, characterized in that the third wiring is not electrically connected to the first substrate.

11. The photoelectric conversion device according to claim 8, characterized in that the avalanche photodiode has a fifth semiconductor region provided in contact with an end portion of the fourth semiconductor region.

12. The photoelectric conversion device according to claim 11, wherein the second wiring supplies a potential to the third semiconductor region via the fifth semiconductor region.

13. The photoelectric conversion device according to claim 8, wherein the second wiring and the fifth wiring are connected by an electrode penetrating the first substrate.

14. Having the first substrate, the second substrate, a first wiring structure laminated on the second surface side of the first substrate, and a second wiring structure disposed between the first wiring structure and the second substrate, The first junction portion included in the first wiring structure and the second junction portion included in the second wiring structure are joined at the joining surface of the first wiring structure and the second wiring structure, and the first insulating member included in the first wiring structure and the second insulating member included in the second wiring structure are joined at the joining surface of the first wiring structure and the second wiring structure. The photoelectric conversion device according to claim 8, characterized in that

15. A photoelectric conversion device having a first substrate having a first surface on which light is incident and a second surface facing the first surface, and a second substrate laminated on the second surface side of the first substrate, The first substrate is A photoelectric conversion element including a first semiconductor region of a first conductivity type and A second semiconductor region of a second conductivity type, A third semiconductor region in contact with the second semiconductor region, A first wiring connected to the first semiconductor region and reading a signal from the first semiconductor region, Including a second wiring provided on the first surface side and supplying a potential to the first substrate, The first substrate is A third surface facing the second surface and a fourth surface facing the third surface, A photoelectric conversion device, characterized by having a transistor which is a part of a pixel circuit for processing a signal output from the photoelectric conversion element, formed on the fourth surface.

16. Having a fifth wiring formed in a wiring structure laminated on the first surface side of the first substrate, The photoelectric conversion device according to claim 15, wherein the second wiring is supplied with a potential from the outside via the fifth wiring.

17. The photoelectric conversion device according to claim 16, wherein the second wiring and the fifth wiring are connected by an electrode penetrating the first substrate.

18. the first substrate, a second substrate, a first wiring structure laminated on the second surface side of the first substrate, and a second wiring structure disposed between the first wiring structure and the second substrate a first joint portion included in the first wiring structure and a second joint portion included in the second wiring structure are joined at a joint surface between the first wiring structure and the second wiring structure, and a first insulating member included in the first wiring structure and a second insulating member included in the second wiring structure are joined at the joint surface between the first wiring structure and the second wiring structure. The photoelectric conversion device according to claim 15, characterized in that

19. a photoelectric conversion device according to any one of claims 1 to 18 a signal processing unit that generates an image using a signal output from the photoelectric conversion device. A photoelectric conversion system characterized by comprising

20. a moving body including the photoelectric conversion device according to any one of claims 1 to 18 a control unit that controls the movement of the moving body using a signal output from the photoelectric conversion device A moving body characterized by comprising